Documentation:
https://msdn.microsoft.com/en-us/vba/excel-vba/articles/application-filedialog-property-excel
https://msdn.microsoft.com/VBA/Office-Shared-VBA/articles/filedialog-object-office

Using FilePicker and FolderPicker uno services.

Change-Id: Ifd3b3fc9c135efb0663d2ef36ecbe2b2fbe6132f
Reviewed-on: https://gerrit.libreoffice.org/39806Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Tamás Bunth <btomi96@gmail.com>